Shetland Chinook legacy remembered

[squib66]

25 years ago today a Boeing Vertol (BV) 234 LR, G-BWFC, on contract to Shell, crashed 2.5 miles east of Sumburgh, Shetland Isles with the loss of 45 lives a catastrophic forward transmission failure which de-synchronised the twin rotors causing the blades to collide.

The Air Accidents Investigation Branch (AAIB) stated that the underlying causes were the inadequacy of a previously accepted test program and the failure of a stringent inspection programme.

Recommendations were:


Certification procedures be reviewed so that all modifications to vital components are adequately scrutinised and tested before approval and more closely monitored after their introduction into service.

The Civil Aviation Authority should report on the progress that has been made towards the early incorporation of a specification for suitable condition monitoring systems into airworthiness requirements for helicopters and indicate the time scale and scope of likely developments.

Requirements relating to the ADELT (Automatically Deployable Location Transmitter) equipment, including location, crashworthiness, protection and power supplied, be reviewed in the light of the accident. (The beacon did not operate due to impact damage to the aft part of the aircraft).


BBC News - Shetland Chinook legacy remembered (http://www.bbc.co.uk/news/uk-scotland-15587942)
25th anniversary of Chinook helicopter disaster which killed 45 men | Aberdeen and North | STV News (http://news.stv.tv/scotland/north/277675-25th-anniversary-of-chinook-helicopter-disaster/)

The event prompted workers begin to stand up for their rights for the first time. Their campaign eventually led to the helicopters being withdrawn.

[Savoia]

Certainly one of the worst crashes in civilian history and probably the second worst Chinook crash of all time after the loss of 46 souls aboard the US Army Chinook which crashed on September 11th 1982 near Mannheim, Germany.

The BIH disaster heralded the end of the type's UK commercial debut but, across the North Sea, Norway's Helikopter Service kept them running a while longer despite a number of in-flight engine failures the year after the BIH tragedy!

Despite several high profile indicents (some of them crew induced) the type remains an indispensable military asset.

[Agaricus bisporus]

As the person who would have been in Fox Charlie's FO's seat had I not been on leave that week I feel there are a couple of points of accuracy to clear up regarding the report and findings of this event.

I have posted the real events on this forum before but can't find the post now - no doubt someone with better search skills will, but the statement " Certification procedures be reviewed so that all modifications to vital components are adequately scrutinised and tested before approval and more closely monitored after their introduction into service. " conveys a meaning at variance with the facts as I remember them. The inadequacies and flawed mods that led to the accident were actually imposed by the CAA themselves in the face of strenuous objections by Boeing and BIH's own engineers who had developed what they considered a sounder and more practical version but as ever the CAA knew better than the aircraft's builder and the world's hugely experienced leading operator of the type.

The problem of internal bolts in the gearbox losing their torque was certainly solved (though clumsily in engineering terms whilst incurring unnecessary cost and downtime) but included a very minor though as it turned out, critical change to the configuration of some washers which allowed salt crystals to lodge in the threads of a bolt, a corrosion pit developed, a crack propagated and the rest is history.

I was a new and junior FO on the fleet at the time but clearly recall the bafflement when the report was published as it bore little resemblance to the events we "knew" about. It was widely considerd a whitewash to cover the CAA's role in causing an unnecessary accident through unwarranted interference in matters that others understood better. Whether my recollection is entirely accurate I cannot say at this remove in time, and will hapily retract any inaccuracies that forumites can identify.

Although it had some flaws - with hindsight BAH should have specified the Boeing-offered mid-cabin emergency exits for instance (wouldn't have saved any lives in this event but would have made a big difference to acceptance of the type by the bears who generally disliked it, largely due to being used to every window being a pop-out as on the S61) the Chinook, which if not already the safest helicopter ever on the N Sea certainly had the potential to be so, was subjected to a concerted, vicious, inaccurate and sometimes hysterical smear campaign by the local "newspaper" which effectively prevented its use on the N Sea again.

The accdent certainly brought about big safety changes throughout offshore operations as listed in the first post, but the tragedy of this accident was that it was totally preventable and should never have happeped.

Of all the types I've flown since, including other Boeing-built products, this is the one I'd go back to like a shot if the opportunity arose. Like most of its pilots I loved the BV234. But then BAH were the only people outside Boeing who really knew or understood it. The remaining three, BISN, BISP and BISR(?) still fly for Columbia helicopters where they have been intensively hauling timber in some of the most arduous conditions extant in the helicopter world ever since. Without significant accident afaik.

That's one impressive safety record, but then the mighty 234 was one hell of an impressive aircraft.

Its hard to believe that dark day was 25 years ago though.
And just for once it is not inappropriate to add RIP.
Because I knew some of them

[zalt]

AB

You have mostly repeated the Boeing line. Boeing actually appealed the AAIB report and the judicial review through out their claims as unfounded.

Boeing's defence, that they were forced to do a modification, is disingenuous as in reality their original design wasn't suitable for a corrosive maritime design anyway and besides the mod was Boeing's and they fluffed it badly.

[SASless]

BAH were the only people outside Boeing who really knew or understood it.

Horse Feathers!

A small outfit called the US Army started flying the Chinook in the early 60's and had millions of fleet hours by the time BAH even saw a Chinook up close.

Perhaps that was the attitude that kept the Chinook from being a Commerical success under British management. What could the biggest operator of the Chinook possibly know as compared to a bunch folks experienced on 61's?

[squib66]

A small outfit called the US Army started flying the Chinook in the early 60's and had millions of fleet hours by the time BAH even saw a Chinook up close.

Well said! I'm not convinced that BIH could have claimed much gearbox design experience either.

Though Zalt's point about the offshore environment is important.

It only took 150 hours with the S-92 in the North Sea for the millions of hours experience of vespel splines on the H-60 to be shown to be irrelevant.

[Geoffersincornwall]

Just after the accident I was on the LHR-ADN flight and found myself sitting next to the CAA Test Pilot. I asked him how a helicopter with 5 gearboxes (3 of which are super-critical) could achieve UK certification just weeks after the publication of the Helicopter Airworthiness Report (HARP) by the same organisation. I didn't get an answer.

This report had been called for on the back of some serious mechanical failures and fatalities amongst the North Sea fleet and focussed, amongst other things, on the criticality of transmission components given the difficulties with creating redundancy within them. The HARP's authors' analysis was that 25 years ago helicopters were being designed using the principles that were applied to the Dakota. In other words the helicopter manufacturers were allowed to use old technology - 50 year-old technology and certification standards. I somehow think that the eye was taken off the ball somewhere along the line!

Seems to me that in the case of the 234 maybe some higher forces were at work. Could any of the 3 players (Shell, BA and Boeing) have applied pressure to the CAA? I wonder if there were any dissenting voices over allowing it on the civil register? I guess if there were then they must have felt justified after the Shetland accident although it has to be said that events since seem to have supported the notion that the 234 was, is, a reliable machine. I have yet to meet a Chinook/234 pilot who didn't love the beast completely.

G.

[ShyTorque]

The Norwegian "Oilies" eventually refused to fly in the BV234 because they didn't feel safe in it. Finally, the employee unions said no more and that effectively grounded the type as passenger transport in the North Sea oil industry.

There were other issues with the aircraft at the time. I watched one lift to the hover at Forus and leave its steerable rear u/c leg behind on the helipad. It was full of oil rig workers at the time, they were not impressed.

Control of another 234 was lost, following an engine problem in IMC. Again it was full of passenegers. That one came very close to total disaster.

I was offered a job on Super Puma the very same day, when the union decided that they would no longer require their members to fly in the type. Obviously, the demise of the 234 left a huge gap in the lift capacity of the company, which needed to be filled asap.

[squib66]

I'd forgotten that the HARP report came out before this accident.

The CAA have never made that report available online but there is an interesting article called 'The Price of Helicopter Safety (http://books.google.co.uk/books?id=GCR8mC5Ea8EC&pg=PA23&dq=The+Price+of+Helicopter+Safety&hl=en&ei=q6C2TrefMoeX8QPkgpSlBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEIQ6AEwAA)' in the New Scientist of 27 Nov 1986 that suggests the research funding came after the Sumburgh disaster.

Geoffersincornwall said:

Seems to me that in the case of the 234 maybe some higher forces were at work. Could any of the 3 players (Shell, BA and Boeing) have applied pressure to the CAA?

You mean a bit like the forces that were put on the regulators when the S-92 MGB failed its oil system certification test on 24 August 2002, weeks before the FAA were due to certify it?

As mentioned above, Boeing appealed against the AIB report leading to an unprecedented independent legal review before the report was issued, held in public:

1989 | 3841 | Flight Archive (http://www.flightglobal.com/pdfarchive/view/1989/1989%20-%203841.html?search=chinook%20review)

AB should note that Boeing were trying, unsuccessfully, to put blame onto BIH...

Unlike the Wells public inquiry (http://www.oshsi.nl.ca/)in Newfoundland after the Cougar S-92 accident, the Chinook review was able to examine all aspects of the accident investigation and aircraft certification (Well's Terms of Reference gagged him form these aspects), and confirmed the thoroughness of the AIB's work.

There was also a Fatal Accident Inquiry held in a court in Scotland too.

[Agaricus bisporus]

Zalt, I am "repeating" no one's line. That was the position as known in the company at the time.
Boeing were "forced" to do a mod? ie told what to do by the CAA against their better judgnent and contrary to established engneering practice when the pevious less intrusive mod was working perfectly. I don't see your point. I can't see how disingenuousness comes into it - or how it relates to your alleged and baseless accusation of unsuitability. How was it unsuitable? I wasn't aware of serious environmental probs before this, are you?

SASless. Oh dear, You imagine I've never heard of the US Army, do you? How patronising. Perhaps the BV234 not being a CH47 has something to do with it (though sharing a great deal of commonality) and this isn't a thread about CH47s.
Perhaps the fact that when the high-time CH47 was overtaken by a two year old fleet of BV234s it was on its nth rebuild and 25years old - with only 3000hrs. The US Army don't do intensive flying like N Sea ops. By the time of the accident the BAH fleet had several times the hours of the next highest in the US inventory. So yes, I think BAH knew a bit more than them about intensive and offshore Chinook ops. Don't you?
Your knowledge of the commercial success (not to mention management attitudes - where did that spiteful little gem come from?) of the 234 is obviously lacking too, it was wiping the floor with the competition - Bristows were terrified of it because they couldn't compete. It needed high intensity high volume routes to work and the Brent provided that, its market was limited but in the right place it was commercially unbeatable.
On what grounds do you imply that pressure was put on the CAA to certificate it? That suggests the CAA were reluctant to do so. Why? What did they know? Please provide us with evidence to support that - so far - baseless allegation. But I won't khold my breath.

The Noggies didn't operate theirs in anything like the same intensive way that BAH did, and the unions stopped them because they (wah! wah" wah") "didn't like it". Poor flowers! Materials technology, gearbox design and manufacturing techniques had made quantum leaps since the early 30s (there had been a world war in between) which is the baseline for the Dakota so I can't see that point is valid. The S61 was of similar - maybe a little earlier - baseline than the CH47 and I don't hear questions over their gearboxes, The Puma had fundamental design faults producing hideous MGB problems for years - but then there are no questions over the safety or reliabilty of Chinook gearboxes are there, apart from a philosophical one of being 3 critical instead of 2? Not a huge difference, is it? Some helicopters have five or six rotor blades, some have two. Could that be said to make the 214 three times safer than a Chinook then? Of course not.

And if there were failures in certification, if authorities took their eye off the ball (for which there is no evidence afaik) then whose fault was that, which was the main point of my post anyway.

Squib, I wasn't aware that Boeing had tried to blame BAH; interesting. Got any links for that? - thanks. But then what else would you expect US liability lawyers to do? That would be just be a normal damage limitation exercise wouldn't it?
I wasn't doubting the thoroughness of the AAIB investigation, it is just that the information on which they based the background - ie the engineering events - differ fundamentally from those (as far as I'm concerned) that were universally understood by those right up close to the event at the time. However nothing alters the fact that pre the second mod the first one - the loctite solution - had worked perfectly and the problem gave ever sign of being solved. Completely. It didn't take long for catastrophic results to occur as a direct result of the second mod that, given the success of the first, was an unnecessary answer to a problem that no longer existed.

[squib66]

BP see the first column of the link above. Note that at that time BAH was BIH.

With respect, you do seem to be challenging the AAIB's conclusions!

The recommendations are clear, Boeing (and other OEMs) should better test such modifications.

So why did Bristow not buy the BV234 if it was such a good thing? Alan Bristow said in 1978 he had rejected the BV234 for both economic and safety reasons:

1978 | 1682 | Flight Archive (http://www.flightglobal.com/pdfarchive/view/1978/1978%20-%201682.html)

Remember that Shell only wanted the BV234 in order to cut out transfer operations from Sumburgh, which were exceptionally expensive due to exorbitant landing fees.

[Geoffersincornwall]

Please read my post more carefully. I asked the CAA TP point blank how come the Chinook was certified in the face of the HARP report findings and received in return a blank stare. Now, you can read that in a number of ways so hence my speculation. Not allegation, just speculation. You can make of it what you will but please don't ignore one of the most important documents ever produced on the state of our industry from a technical point of view.

I haven't read the HARP report in quite a while but my recollection is that the comment about the Dakota was theirs not mine.

G.

PS - Have just searched the web for half and hour looking for a copy of the Helicopter Airworthiness Review Panel (HARP) report of 1984 otherwise know as CAP 491, but cannot find a copy either to read or buy. Has anyone got one in their library that they can scan and make available please.

[SASless]

AB,

Again....you just do not know what you are saying...



The US Army don't do intensive flying like N Sea ops. By the time of the accident the BAH fleet had several times the hours of the next highest in the US inventory. So yes, I think BAH knew a bit more than them about intensive and offshore Chinook ops. Don't you?


I suppose my Army Flight Records are all a fabrication then....and my first hand experience on the aircraft...along with my North Sea experience bar me from having a basis upon which to draw my obervations.

We flew the machines approaching two hundred hours per month under combat conditions....maintained them in the open....and carried loads much more stressful than did the BAH aircraft.

The Army does not operate a system of maintenance as do Civilian Operators and the aircraft do not accrue the airframe hours per individual airframe...but when one has 500 of the things....and over Ten Years experience operating them....there is a corporate knowledge that transcends a fleet operation of a mere handful.

The 234 is different from the CH-47 in exactly the same way the 61N and Sea King differ....only by degrees.

What did not change was the usual British institutional arrogance towards accepting advice from anyone else no matter how qualified the source.

That reluctance is of historical record, noted, and well known. The sayingis "Teach a Brit today....and he will tell you how to do it tomorrow!" That has never changed.

It also appears alive and well within your posts.

[Fareastdriver]

A bit heavy SASless. Fish not biting today.

[zalt]

There is this story on a US Army loss on 1982:
The crash of Boeing's CH-47C Chinook 74-22292. (http://www.chinook-helicopter.com/history/aircraft/C_Models/74-22292/74-22292.html)

http://www.chinook-helicopter.com/history/aircraft/C_Models/74-22292/74-22292_one_point_five_seconds_before_impact.jpg

[industry insider]

AB

You are correct, Bristow was terrified of the BV234, just not commercially.

Bristow actually had 5x BV234 ordered but contractual negotiations with Boeing broke down over penalties Bristow wanted for any shortfalls in performance. There was also an internal memo generated by the Operations Department looking at the implications of a ditching. This scared the heck out of Senior Management and combined with the contractual issues above, the order was cancelled.

Instead, the company went on to be involved in the development of the AS332L with Aerospatiale as it was then.

[Agaricus bisporus]

As the Bv234 was almost as wide as it was long and had the stability of a barge the implications of a ditching were that it would be almost impossible to overturn, thus it did not even need loatation gear. The Puma especially is notoriously unstable on the water and the failure of one float - a frequent, even common event, would very likely result in a capsize of most other, if not all other N Sea types. What on earth do you mean - I don't understand.
If you are referring to the lack of emergency exits in the cabin I have already addressed that matter. An option was available had Mr Bristow wished to take it up. "Negotiations broke down---shortfalls in performance" Er, what shortfalls in performance? I don't recall any. Surely not Bristows asking too much and then demanding guarantees? That just sounds to me like Bristow Bluster. I can understand that Bristow who knew first-hand how fickle helos can be was reluctant to put that many people into one machine lest there was a disaster, a suggestion published elsewhere. He was astute enough to see that so many bodied would make unacceptable PR, but that is a value judgement. My bet is he knew the 234 to have a limited market routes wise and that 2 companies chasing very few contracts would result in a profitless pissing contest and airframes being underused. The capital outlay and lack of obvious resale markets probably made this an opportunity to walk past, but being Bristow he couldn't and wouldn't say that so he came out with some bluster to cover it. As it turned out the 4 machines did pretty much fill the niche, and very profitably too. But I bet there wasn't room for 5 more. And from then on he missed no opportunity to snipe and slag it off because he couldn't compete in any other way.

It is indeed curious how contrary people can be on this forum against the presented evidence. It is confidently assumed that the CAA dishonstly colluded with industry to certificate an aircraft that is implied, with no shred of evidence to support the claim - that they somehow "knew" to be unsuitable/unsafe. (I'm curious, how could anyone know that, and if they did, how come it wasn't/isn't public/industry knowledge?) The dishonesty of the CAA is taken as read yet the suggestion that an AAIB report might not be completely accurate (when it is repeating a line given it by the "dishonest" CAA) is scoffed at. Why is one unquestionably honest and the other unquestionably not? Implications that an aircraft was thought fundamentally unsafe are made repeatedly with no shred of evidence to support it, despite other operational types having horrendous problems and no complaints of CAA collusion or unsuitability there. SASless apparently thinks that 3000 hrs accrued in short bursts of 200hrs per month over 25 years somehow says more about a machine's durability than three times that accrued in six, and confuses the corporate knowledge of 500 low hours airframes with the specific experience of three times the hours at high intensity which is the subject we are actually discussing. The inconvenient fact that Boeing themselves were the engineering authority throughout all of this is conveniently forgotten. Or perhaps they know nothing compared to the US Army too...

SASless, in reality most of the world would name a quite different English-speaking nation from the description you gave...And that's a fact.

So there you have it. A sound, safe transport helicopter that for some reason even helicopter experts love to rubbish without good reason or evidence while ignoring far more serious shortfalls on its competitors. Poor Chinook, it deserves better.

[Phone Wind]

As the Bv234 was almost as wide as it was long and had the stability of a barge the implications of a ditching were that it would be almost impossible to overturn, thus it did not even need floatation gear.

It is indeed curious how contrary people can be on this forum against the presented evidence

1988 'Flight' archive:

...of a bypass valve.
The report highlights a series of shortcomings in the operation and maintenance of the helicopter. It says that a
number of screws on other actuators were grossly undertorqued and that the operator, British Airways Helicopters, had failed effectively to investigate or resolve similar occurrences before the accident.
A damaged rear cargo ramp seal had allowed water into the ditched helicopter, which capsized about 80min after ditching.
Pre-flight flight control

Luckily the weather was calm at the time so all 47 passengers and crew were rescued. Even more luckily, the aircraft was ditched only 6 miles from Cormorant A so 2 Bristow SAR equipped Bell 212s, Rescue 45 and 46 were on the scene just a short time after. Had the aircraft ditched at night, in bad weather a long way from the Brent complex who knows what might have happened. :confused::\

The Chinook was a horrible aircraft to be a passenger in. It was uncomfortable and despite the large cabin, the relatively small, high windows made it feel cramped and many of the passengers, who were scared of flying in many helicopters, were even more scared by the Chinook. My bag being ruined by a large hydraulic leak into the baggage compartment was the last straw and afterwards I always flew fixed wing to Sumburgh and then in an S61 rather than the Chinook :=

[industry insider]

AB

I am not arguing with you about the performance of the BV234 either in normal operations or in the event of a ditching, I am relating the events of 1979-80.

The performance issues which led to BHL cancelling the BV234 order related to contractual performance, not actual aircraft performance.

Bristow wanted added penalty clauses for what was then a very expensive aircraft. The clauses related to aircraft availability to the customer. BHL wanted to be compensated if the customers (Shell and BP) declined to pay a portion of the standing charges due to aircraft being unserviceable. Offers of consignment spare parts failed to satisfy Bristow enough to prevent cancellation in 1980.

It was also decided that 2x 332Ls would offer greater flexibility at a cheaper cost to the oil companies than contracting 1x BV234 which, if unserviceable required significant backup capacity to transport 44 passengers.

[SASless]

Poor Chinook, it deserves better.

Yet the old girls labor on...day after day...year after year...working their hearts out...making money for whoever owns them. Columbia took the same machines and we see how that turned out...a success.

The military Chinooks are scheduled to be in service till close to 2050 or some unimaginable time....and folks skip over all of this.

She's a wonderful Bird....has always been...and always shall be!

To know her is to love her!

[Fareastdriver]

To know her is to love her!

Unfortunately, in the North Sea, she lost the confidence of her passengers.

End of story.

[Colibri49]

Never having flown the Chinook. nor having been employed by that company except for a 3 month interlude, I feel eminently qualified to comment on its suitability as an offshore public transport machine.

I have been employed as a North Sea pilot for 3 decades and it takes no great intelligence to appreciate that the inherent weakness of the Chinook design is the importance of keeping the rotors synchronised.

Hence THREE of the five gearboxes ARE SUPERCRITICAL as a failure in any one of them will cause the rotor blades to clash. This is not true of other conventional helicopter designs, where a failure in either gearbox isn't necessarily going to have immediate fatal consequences.

From vague memory, the Chinook ditching certification trials were performed in a wave tank, probably using a model airframe in a relatively gentle sea state. But on an average North Sea day with wave heights of around 3 metres, the low-mounted Chinook front rotor would inevitably hit a wave before the rotors could be stopped and the ensuing breakage of a synchronising driveshaft or gearbox would allow front and rear rotors to clash.

Fatalities from flailing blades chopping into the cabin are almost guaranteed. Now who's going to try and convince me that I shouldn't give opinions on something I know nothing about? Don't waste the effort. Non-BAH/BIH pilots were discussing this aspect long before the disaster; I remember it all too well.

[Rigga]

Oh, the folly of...

"3 of the five" may be 'supercritical' but no less and no more critical than "1 out of one" - It's not as though you disconnect everything after every landing - or fold blades every night? - A bit of a non-argument really.

Having been onboard during Chinook water landings I can say that they can cope well with some spashy scenes - probably just as much as others can. I cant say about Fwd blade clearances, but I'm sure there are less worried about tail blades.

Having worked on the end results of three CH47 incidents - no-one was chopped up by blades coming through the sides, although at least two people I know were pushed off their seats.

When walking towards one incident I asked a senior pilot if the lack of a cockpit roof, rotor and gearbox would shake him? - to which he said that many other helis would have shaken themselves apart in the air, well before this particular event - in which all aboard survived without any significant injuries.

Your statements seem to be myth-guided?

[ShyTorque]

When walking towards one incident I asked a senior pilot if the lack of a cockpit roof, rotor and gearbox would shake him? - to which he said that many other helis would have shaken themselves apart in the air, well before this particular event - in which all aboard survived without any significant injuries.

This one BB's post maintenance incident, again where a MRB gearbox seized in the hover? He told me how, after the aircraft fell to the ground, he reached up to the top panel shut down the engines, only to find the entire control panel had gone AWOL, along with the roof; he was sitting in an open topped cockpit.

The entire top deck was empty, rotor system, gearboxes, pylons, the lot, all gone.

[squib66]

Rigga 3 is still greater than 1.

Are the S-61 stories really relevant?

[SASless]

Hence THREE of the five gearboxes ARE SUPERCRITICAL as a failure in any one of them will cause the rotor blades to clash. This is not true of other conventional helicopter designs, where a failure in either gearbox isn't necessarily going to have immediate fatal consequences.

Failures of MGB's on all helicopters have nasty results....cast iron failures are usually very fatal very quickly very certainly!

Yes the Chinook has three very important gear boxes...FWD, AFT, and Combining....and yes...if one of them fails you have had the schnitzel...but in how many other helicopters does one not become sausage following a MGB failure?

One can argue there is three times the chance..but that is a fallacy. One must compare the actual rate of MGB failures by aircraft type per flying hour and then make an argument based upon that data.

I feared something getting under the Synch Shaft far more than I ever worried about a Gear Box failure....as they were pretty much unheard of whereas the loss of Synch shafts had occurred. Just as riveted ends of control tubes happened for a while. We even had blades rotatiing in the cuff due to Incidence Bolt failures....but yet the Chinook matured and those problems were cured/solved and became things of the past.

Bad maintenance seems to be the major culprit in any aircraft loss these days....except when Pilots forget how to move the sticks after letting the Auto Pilot do the driviing too much.

Much was made about Quill Shaft failures....but not once did I ever hear of that particular shaft failing as it was so over engineered and built way beyond the strenght it needed to be...that it was more an Old Wive's Tale than a genuine risk.

Anyone that diss's the Chinook is just suffering from Penis Envy in my book.

[Rigga]

ShyTorque,

That is BBs soft-top incident indeed. And I was asking a 7 Sqn S/L at the time. my job was to remove the Aft Xmsn - which I did...horizontally.

"...where a MRB gearbox seized in the hover?"
No, it didn't. The Xmsn input shaft thrust bearing had been installed the wrong way round. It moved and allowed the drive gear to dissengage.

SaSless...

Impedence Bolts. I was lucky enough to have a fascinating conversation with an AAIB investigator regarding Impedence Bolts while investigating another accident.


...No. I wasnt working on any Sqn at the time.

[pumaboy]

Here is a video of a spanish Military CH-47 Chinook making a water landing and remember the civil version was wider due to the extra large fuel tanks.

CH-47 Chinnock - Landing in the sea - YouTube

[Fareastdriver]

I think it is obvious to everybody that that is not a water landing... Big rotorwash, coning angles etc. That is just washing the dust off the bottom of the aircraft. There is a SK76, without flotation gear inflated, that has inadvertently gone into the water deeper than that and has flown away.

[Colibri49]

I'd like to see that "water-skimming" exercise done with 3 metre waves, or alternatively with the collective fully down in 1.5 metre waves. Either way the outcome wouldn't be pretty.

[SASless]

How does the 225/Super Puma do in the same conditions of three meter waves and no floatation? Any reason there is a move to add "Righting" floats to keep the aircraft right side up or at least on one side rather than wrong side up?

Compare apples to apples!

[Colibri49]

They (225/Super Puma) don't have inter-meshing rotors. That's been my central point since I made my first unwelcome comment. I'm by no means the first to comment on this and I can't understand why others turn a blind eye to the consequences of rotor synchronisation being lost after one rotor hits a wave before the other.

[gasax]

I'll join in on colibri's side.

I worked with 2 of the people who died in that crash and flew as self loading freight 4 or 5 times on Chinooks - so I do not have a high opinion of them.

From the freight's viewpoint they were noisy, cramped and difficult to get into and out of - and that was without there being a problem and having to use the limited escape routes.

Helicopters tend to be very intolerant of transmission failures generally - introducing a variety of new and interesting failure modes in addition to those of a single rotor helicopter, means that either the design, engineering and maintenance has to be considerably better to maintain the SAME level of safety.

That situation may now have been achieved with the military variants - but somehow I doubt it. Certainly it has its uses in terms of heavy lift but not for people. Or at least not people who can choose.

[Agaricus bisporus]

It is telling how virtually all pilots who have flown the Chinook love and trust it while its pax who have flown in it 3 or 4 times seem happy to join in a safety-centred debate slagging it of and implying it unsafe on the basis of it being "noisy and uncomfortable" or leaking oil on their bags...
I think this amply illustrates the difference between decisions/judgements made from a position of knowledge and kneejerk prejuduices made with no knowledge or factual basis whatsoever. The tragedy is that in this crazy world of ours the latter is sometimes allowed to overrule the former when in reality it isn't even worth acknowleging. I think all is's pilots would agree that the 234 was lacking in comfort - it was cramped, 40 seats - one less row would have been better, the windows were small, but what's that got to do with anything? Vibrate? Nonsense. Not in the cruise it didn't. The dynamic vib control (the saddle-tanks were mounted on nodal beams) worked well but could and did cause larger than normal vibration at certain phases of flight, usually t/o and landing. But so what? That's a transient comfort matter, nothing related to safety. Emergency exits I agree were insufficient and I think all the pilots acknowledged that too. That was an unforseen error made at the time of ordering them.

I am not convinced by the argument that blades would strike the water in a ditching either, while turning the front blades were well out of harm's way and only drooped at very low speed when a strike would not be dangerous. Not many waves are steep enough to reach a point perhaps 3-4 metres high before they've lifted the hull just beyond. Sounds rather far-fetched (no pun intended) to me, and I'm sure must have been examined in the certification process. A ditching in such severe conditions would overturn a conventioonal helo almost instantly and almost certainly be unsurvivable even if egress was made. I know for sure which one I'd prefer to be in.

And to the poster who triumphantly pointed out the capsizing of the ditched BV234 (I didn't think it would take long for that pavlovian response to appear) for your information this had nothing whatsoever to do with the aircraf's stability as you yourself inadvertently pointed out. It floated as stably as a barge but eventually overturned due to water entering the cabin over a period of time past the aft bulkhead dam, a rubber seal like a car door seal had been torn by passing personnel and baggage over the preceeding months and did not seal properly. The hull loss was directly attributable to a ten dollar piece of rubber seal. That was an expensive lesson on the back of a safe and successful ditching that proved the types ability to cope easily with the event.

[JohnDixson]

The following pics from a February 1965 test at Ft Rucker on a new A model with a rear dam kit:

( Probably should add, relative to the discussion at hand, that this machine did not have a rotor brake. Surely the 234 would have had one, and most likely the emergency procedures would have cited an immediate, full on application after a water landing in high sea state. I don't know the 234, but one would assume the rotor brake disc would be located between the combining box and the aft transmission. 234 pilots can correct this info.

http://i1205.photobucket.com/albums/bb434/johndixs/CH-47AWater_0001.jpg

http://i1205.photobucket.com/albums/bb434/johndixs/CH-47AWater_0002.jpg

[Colibri49]

"Vibrate? Nonsense. Not in the cruise it didn't."

One of my colleagues used to fly it regularly as a co-pilot on flights between Aberdeen and the East Shetland Basin. He told me that it was not uncommon for him and others to get off the co-pilot's seat during the cruise to get some relief from the vibration.

Exactly how he did that I don't know. Whether he just lifted himself partially from the seat for a short while, or whether he vacated the flight deck is irrelevant. What is certain is that he found the vibration sufficient to give him headaches and backaches.

I can empathise with your sentimental attachment to the Chinook. I'm sentimentally attached to the S61N, but that doesn't make me blind to its weak points such as being seriously underpowered on one engine.

Have you actually seen the steepness and short intervals of waves on the North Sea on a rough day? If you think that one of the rotors (particularly the front) wouldn't contact the water until the blades were drooping to a standstill, then you need a reality check.

Yes, I'm envious of those who've flown it, but not to the extent that I'd have wanted to spend much time in the Chinook over rough water. This line of argument is already pointless, so I'd better just leave you and all with real experience on the type to selective reminiscences.

[SASless]

Do I know what the North Sea looks like....Yes.

Given a choice of the Chinook or any other type that is or has ever worked the North Sea Oil Support industry.....without a single second's hesitation it would be the Chinook (234) as first choice!

As to my choice of aircraft to ditch in the North Sea...again without a second's hesitation it would have been the 234 as it is one very large boat with a lot of inherent stabilty due to its length and width.

Likewise as a Pilot...the spring assisted jettisonable crew doors is a big plus. No hunting for a way out in the Chinook.

As a passenger...that might be a much different kettle of fish. The seating decision was made by the customer, the exits were dictated by the customer, thus I cannot fault the aircraft for that situation...but do fault those making the decisions.

I have played boat captain in the Wokka.....and she makes a very fine boat she does. She was designed to be landed in the water as a part of normal operations. That is a good start if one has to "ditch".

Is not one of the questions the Industry struggles with is when to limit aerial operations due to Sea State conditions?:mad:

And...it is the one that generally has been ignored the most all these years and still does not have a effective answer in place!:ugh:

[Fareastdriver]

Not knocking the aircraft, but; the exits were dictated by the customer, I would have thought that the holes in the side were put in by the manufacturer. He would have modified those holes according to the regulations of the country that the aircraft was to be registered in. There was no further requirement in this particular case so the customer had no decision to make.

I was among the first to volunteer to fly the Chinook when it was mooted that Bristow may buy them. I missed out on that for obvious reasons. I regret not being able to fly it as I would have done if I had remained in the Royal Air force. However, at the end of the day, the 332L was the better helicopter for the North Sea; and this has been proven by the almost universal application of it worldwide on long range offshore applications.

This thread is getting like the Harrier thread on the military forum. It's gone, sorry, there's nothing you can do can bring it back. Let the subject rest.

[ShyTorque]

I think that some here are forgetting one very important thing.

The pilots only fly the aircraft. Like it or not, the passengers of a civilian aircraft are the customers. Nothing much else counts.

[Agaricus bisporus]

Colibri, it can be utterly maddening how some people argue from the specific to the general on this forum, and how it seems to be necessary to write caveats to every contrary eventuality when making a simple point.
I said it did not vibrate in the cruise and thought I'd qualified enough with my extensive explanation. Evidently not enough though... as I was discussing the pax it didn't occur to me that someone might want to bring the flighdeck into it. My mistake! The LH seat in the 234 was sited at probably the strongest vibration node in the aircraft and could be uncomfortable at tines. One of those frequencies was resonant freq of the end of the human nose which made it tickle and bring on a long-tern desire to sneeze. I certainly never felt the need to get out of my seat or suffered any physical effects and am a bit surprised anyone else did, I don't recall the vibes being that bad.

I haven't seen anything sentimantal here ignoring obvious faults - indeed the (relatively few) faults are being discussed in detail. Pilots tend to be more practical than sentimental which is why those who have the knowledge of this machine tend to prefer it over other more conventional craft, especially those that were unergonomic, labour intensive and grossly underpowered & short on range, frequently developed red-hot gearboxes or depended on the 100% success rate of several tetchy and delicate gasbags or they were guaraneed to fall over when ditched. I'd respectfully suggest that preference is founded on a sound Professional judgement of the respective merits of the various types rather than on sentimentality, and the result is petty conclusive.
And finally, no, as a Chinook, Seaking, S61 pilot, Naval person, Yachtsman and sand-castle builder I've clearly never seen waves on the N Sea. (sigh) Next question?

I wouldn't propose the 234 for anything but short public trips, but the N Sea was and is not a "public" environment. The pax are travelling to work on company provided transport so can't expect the levels of comfort that apply to bucket and spade trips. It is no different to miners going to work standing in a dark metal cage or fishermen/offshore windmill workers hanging on to a railing for grim death. I'd say they have it pretty good compared to many.

[Snarlie]

I can vouch for the fact that Alan Bristow seriously considered purchasing the BV 234 and that he led a team to Boeing for an in depth assessment. As a hugely experienced test pilot and with the support of gifted engineers, he did not like what he saw. The negotiations that followed were really only ever going one way and that same team then addressed the redesign of the AS 330J Puma with Aerospatiale to incorporate elements of the AS 331, which I saw in a hangar in Marignane, and came up with the AS 332. Mr Bristow saw this option as addressing the wider needs of the oil industry at that time, not merely the Brent field, hence the initial order of 35 aircraft.

It has to be agreed that the BV 234 had its problems at first, having a beer or three with Dave Humble in the Skean Dhu after he had spent all day wearing a rectal thermometer to gain data on his core temperature after prolonged exposure to vibration was only ever a one way conversation!

The BV 234 was limited in speed fairly soon after introduction due to vibration, leading to the story about the official complaint for ungentlemanly conduct prompted by the AS 332 which overtook whilst lowering its undercarriage. The AS 332 was not without its own blemishes but do not let the facts of the 234`s shortcomings be obscured by the partisan bias fuelled by the `Strike of 77` as would appear to be happening in AB`s thinly disguised rant.

[ShyTorque]

It is no different to miners going to work standing in a dark metal cage or fishermen/offshore windmill workers hanging on to a railing for grim death.

That just about says it all.

[SASless]

Probably the final nail in the coffin....there was a survivor of the Chinook Gear box failure....not so the S-61's Spindle slingings or the Bond Super Puma head shucking.

Says everything about Fate, Luck, and Divine Intervention...and not anything about Engineering.

[Agaricus bisporus]

Snarlie, a piece of advice if I may;

"Rant" Best not to use words if you don't understand them. Dictionaries are readily available, it seems you need one. Look it up.

1977 strike. Had you made even a token effort to read this thread you'd see that I was a new FO at the time of the accident, 1986. It would be readily apparent to anyone who cares to think for even an instant that that was ancient history (9 years previously) and I could have had no connection with it whatsoever. Whatever made you come out with a random brainfart like that I cannot imagine.

Look up "unwarranted" and "assumption" while you're at it too.

[SASless]

Funny how Union movements within the Helicopter industry generate such strong support and dissent simultaneously. Granted those that have benefited from such movements without raising a hand oft times are the very worse critics.

Anyone that says Unions are all evil....need to look at their pay cheque one payday and think what it might have been sans Pilots getting together and demanding better wages, benefits, and working conditions!

[squib66]

Anyone that says Unions are all evil....need to look at their pay cheque one payday

Funny you should say that SASless, but its worth remembering that when I started this thread, one of the points that was being made in the press coverage on this accident was that it was union power that forced the removal of the BV234, not for the financial gain of their members but to reduce the chances of so many being killed at once again.

[Attila]

Actually, SAS, there were TWO survivors of the gearbox failure. One was a passenger and the other was Pushpa Vaid, the captain.

[Rescue1]

After 26 years a Committee has been formed to erect a Memorial to all those that were killed in this crash along with three other Incidents around the waters of Shetland.

On the 31st of July 1979 Dan Air flight 0034 an HS748 aeroplane failed to safely take-off from Sumburgh airport with the loss of 17 lives. Seven years later on the 6th November 1986 a Chinook helicopter returning from offshore, suffered mechanical failure 2.5 miles east of Sumburgh Airport with the loss of 45 lives. Four years afterwards, on the 25th of July 1990, during a shuttle operation in the Brent oil field an S61 Helicopter ditched beside the Brent Spar installation, 112 miles north-east of Sumburgh with the loss of 6 lives. On the 14th March 1992, whilst transferring oil workers from the Cormorant Alpha platform 102 miles north-east of Sumburgh, an AS332L helicopter crashed with the loss of 11 lives.

the website is here Home (http://www.sumburghairportmemorial.co.uk/index.html)
if anyone would like to contribute towards the Memorial the committee would be eternally grateful.
there is also a Facebook page if you could click the "Like" button that would also help get this out there for more people to see.
Thankyou in Advance

R1

[CharlieOneSix]

Rescue 1 - I see from the list of contributors to the memorial that you are already in contact with the widow of one of the Dan Air pilots who used to be one of my neighbours. I'm also in contact with the widow of one of the passengers and will let her know about the project and website details.

[Rescue1]

Thankyou CharlieOneSix if anyone else knows of any other relatives or survivors of any of these incidents could you do the same please, They are hoping to have the Memorial opened next May.
Regards
R1

[Oldlae]

Snarlie.
I was at the Connecticut Lycoming factory at the time that Alan Bristow announced he didn't want the 234. I was investigating a failure of a T53-13 Bell 205A-1 engine in Indonesia at the time. I was quizzed by several Lycoming executives as the 234 engine (T55) had failed some tests on a test bed. It was thought by them that I had heard (I hadn't) about the problems and telephoned Alan.